The present invention relates to the use and placement of catheters in the body of a patient and, more particularly, to a new method and system to facilitate catheter exchange during dilation procedures such as angioplasty.
Catheters are widely used for a variety of medical procedures involving insertion of catheters at various locations within a patient. Catheters are used in angioplasty procedures to open stenoses in the treatment of vascular diseases throughout the vascular system, including in the coronary arteries.
A typical angioplasty procedure involves the placement of a dilation catheter having an inflatable balloon in a deflated state at its end within the stenosis and then inflating the balloon causing it to radially expand the artery until the artery is re-opened to establish an acceptable rate of flow. The balloon is subsequently deflated and removed from the artery. In a similar procedure, a sleeve shaped deformable stent is deployed into the artery and radially expanded by inflation of a balloon positioned within. The stent remains in place in the artery after the balloon is deflated and removed to maintain flow in the artery.
The placement of the dilation or balloon catheter and the balloon usually involves the use of a guidewire which is advanced through the patient's vascular system to the location that is to be treated. In the typical angioplasty procedure for the coronary artery a guide catheter is introduced into the patient through the femoral artery and into the aorta, and then subsequently through the osteum to access the coronary artery. The guide catheter remains in place throughout the procedure to serve as a means for the guidewire and the balloon catheter to access the artery.
The balloon catheter threaded onto the guidewire prior to insertion into the patient. The guidewire, which is typically made of stainless steel and platinum having a diameter of about 0.0100-0.018 inches, can be formed with a slight curvature at the end which enables the physician to steer the guidewire while advancing or withdrawing.
The balloon catheter is an elongated, flexible member having two longitudinal passages therethrough and a balloon at its distal end. One longitudinal passage provides a sleeve passage for receiving the guidewire. The other longitudinal passage provides a fluid or gas conduit for introducing pressurized fluid or gas from external pressurized means to the interior of the balloon to inflate the balloon. The two longitudinal passages may be provided adjacent to each other or in coaxial alignment whereby the inner passage receives the guidewire and the outer passage carries the pressurized inflation medium.
The guidewire is inserted through the balloon catheter such that a portion of the guidewire extends from the distal end of the balloon catheter and another portion extends from the proximal end. Together the guidewire and the balloon catheter are inserted into the proximal end of the guide catheter until the balloon reaches the distal end of the guide catheter. At this point, the physician holds the balloon catheter in position and, using fluoroscopy to view the procedure, pushes the guidewire past the distal end of the guide catheter, steering the guidewire into a selected artery. The guidewire is advanced until it reaches the desired area of treatment. The distal end of the guidewire is then pushed past the stenosis.
While holding the guidewire in place, the physician advances the balloon catheter along the guidewire. When the balloon reaches the area of the stenosis to be treated the inflation medium is injected through the balloon catheter and into the interior of the balloon. The resultant inflation of the balloon expands the inside wall of the artery in the region of the stenosis thus re-opening blood flow in the artery. Similarly, in stenting procedures, the inflation of the balloon expands and permanently deforms the stent so that the stent maintains a sufficient diameter opening in the artery for adequate blood flow.
Sometimes during angioplasty procedure it is necessary to use more than one balloon or stent to treat a blocked or dissected artery or to exchange a first balloon for a subsequent balloon of a different size. In order to carry out the exchange of a balloon catheter it is necessary to remove the balloon catheter by holding the guidewire in place and manually retrieving the catheter. The balloon catheter is withdrawn until it is completely out of the patient and past the proximal end of the guide wire. A new balloon catheter is then re-inserted over the guidewire and advanced until the balloon is positioned at the location of the area to be treated by the procedure described above.
During various inter-vascular procedures such as angioplasty or stenting, especially during catheter exchange, it is desirable to leave the inserted guidewire in place because the presence of the guidewire in the artery may cause the artery to react by constricting. Also, predilated lesions can become dissected during angioplasty procedures. Thus, removal of the guidewire during such a constricted or dissected state may make re-insertion of the guidewire difficult or impossible. Throughout a procedure using a guidewire and catheter it is essential to maintain stable axial positioning of the guidewire tip to prevent inadvertent withdrawal of the guidewire from the area to be treated and to prevent inadvertent forward advancing of the guidewire which could cause damage to tissue or otherwise endanger the patient.
In order to remove or withdraw a balloon catheter while holding the guidewire in place, a difficult and time-consuming procedure must be followed. This is because in order to remove the balloon catheter from the guide catheter the proximal end of the guidewire must be held to prevent axial movement and buckling of the guidewire. Then the entire length of the balloon catheter must be withdrawn past the proximal end of the guide catheter, requiring the guidewire or an extension thereof to extend at least the length of the catheter beyond the proximal end of the guide catheter when the balloon catheter is inserted fully into the patient. Alternatively, the balloon catheter and guidewire must be held at the proximal end of the balloon catheter and moved together in very small incremental steps while the guidewire is pushed back into the patient by the same incremental amount between each step. Once the balloon catheter is advanced past the proximal end of the guide catheter, the guidewire can be grasped adjacent the proximal end of the guide catheter to allow quick removal of the balloon catheter. The balloon catheter is removed and a new one is inserted over the guidewire and advanced to the area to be treated, with the guidewire axially maintained in position. Such a procedure is cumbersome and, in some instances, poses an increased danger to the patient when time is especially critical.
The above-described procedure usually requires at least one assistant, and sometimes two, to assist the primary physician in manipulating the angioplasty system components. Due to the length of a typical guidewire and balloon catheter assembly, it is sometimes difficult for the physician to simultaneously reach and manipulate the angioplasty system components. At the same time, the physician must also maintain watch, via fluoroscopy, over the positioning of the components within the patient's body. Because of the need to manually move the guidewire and balloon catheter relative to each other as described above, with no secure means of fixing one or the other to a stationary point in the surrounding environment, approximations with respect to the positioning of each must be made by the person or persons moving each component. While this method is already prone to error when only one individual is handling both components, the likelihood of error is heightened when two or more individuals are assisting in coordinating the relative movement of the components. The need to accommodate additional personnel and to carefully synchronize their movement and accuracy adds to the complexity of the procedure, adding potential risks and danger.
In all procedures, including angioplasty, it is desirable to minimize radiation exposure to the patient, the physician and the attending staff that is attributable to the use of x-rays in fluoroscopy technology. The physician and staff are subject to cumulative radiation exposure over time. In angioplasty procedures, it is necessary to use a fluoroscope to visually monitor the relative positions of the guidewire and balloon or stent inside the patient's body with respect to each other and to the patient's body. If means were provided to reliably maintain the position of the guidewire relative to the patient, the fluoroscope would not need to be relied upon to monitor the guidewire position or the position of the balloon, until the balloon is positioned near the distal end of the balloon catheter. Up until that point, the physician, if provided with reliable means to secure the guidewire and prevent its buckling could rely on the already commercially available length markings provided on certain balloon catheters that correspond to guide catheter length in order to know the relative position of the balloon.
It is therefore desirable to provide means and a method to quickly and safely install, remove or exchange balloon or dilation catheters using a guidewire.
Various known devices such as those described in U.S. Pat. No. 5,255,690 and U.S. Pat. No. 5,454,785 provide a hollow tube for guiding the withdrawal of catheters over guidewires. In those devices, however, semi-flexible materials having diameters sufficient to permit clearance for the catheter and the attached structure such as a Y-adapter are used for the tubes, resulting in lateral clearance around the enclosed guidewire. Such clearance allows lateral guidewire play and provides inferior support against buckling of the guidewire, which could disturb the position of the guidewire tip inside the patient. Also, such buckling may cause frictional forces between the guidewire and the inside wall of a balloon catheter, causing inadvertent withdrawal of the guidewire when the balloon catheter is removed. Furthermore, such known devices do not facilitate easy lateral installation of the guidewire into the guiding device during catheter exchange, which enables safe and rapid exchanges that are critical during such procedures. Instead, such devices require axial insertion of the hollow tube over the proximal end of the guidewire or guidewire extension.
It is therefore an object of the present invention to provide an apparatus and method for quickly, safely and accurately installing, removing or exchanging a catheter while avoiding the above-identified problems and shortcomings of the prior known devices.